The present invention relates to a parallel optical switching apparatus which is used as an optical neurocomputing basic element having an optical arithmetic apparatus and learning function for optical computing. The present invention can be used also as a basic device for a subscriber system or an optical transmitter of an optical network.
The arithmetic speed of the prior art of a supercomputer is about 1 Gop/s max. and the parallelism of a very large scale parallel machine which is represented by a connection machine is about 10.sup.4. An optical computer or neurocomputer has been proposed on the assumption that the arithmetic speed and parallelism will be extended in the future. As a most basic model, an interconnection model is discussed in N. H. Farhat, "Optical Implementation of Hopfield Model", Appl. Opt., Vol. 24, No. 10, pp. 1469-1475.
This model is used to perform arithmetic of multiplication and sum of an input vector X(n) and memory matrix W(n, m) by light and structured so that an output vector Y(m) is obtained by representing the input vector by the optical intensity of an emission element, spreading it in one direction by a cylindrical lens, and modulating the memory matrix (for example, transmission factor) so as to focus in the orthogonal direction. The processing is performed by multiplying the output by a threshold function using this basic structure and feeding back it to the input side. An example that an attempt is made to perform the above processing using a 1-chip structure is discussed in IJCNN, Washington D.C., 1989, Tech. Digest, Vol. II, p. II-477 as an electronic controlled circuit by Ohta and others.
An example that this Hopfield model typed model is applied to an opto-associative memory is reported in Technical Report of The Institute of Electronics, Information and Communication Engineers OQE87-174, p. 39-45, 1988 in detail.
Furthermore, an example that a memory correlative matrix is realized by multiplexing different frequencies or phases for positive and negative values of memory information or the above positive and negative values by alternative time division and by driving them is proposed in Japanese Patent Laid-Open No. 2-45815.
In an optical network system, an art for forming not only the transmission network but also the optical translation network as optical circuits (laser beam) is essential. To realize this optical transmitter, an optical switch is under study and a tree type semiconductor optical switch array is indicated in Report of SWITCH ARRAYS FOR PHOTONIC SWITCHING: STATUS REVIEW AND PROSPECTS (L. Thylen et al, Technical Digest of IEEE Global Telecommunication Conf., San D-iego, Calif. USA, Dec., 1990, Paper 706B.1).